1. Field of the Invention
The present invention relates to a multi-mode communication device, and more particularly, to a multi-mode communication device which is operable in either GSM/WCDMA mode.
2. Description of the Related Art
Global System for Mobile Communications (hereinafter, referred to as “GSM”) is an international standard for cellular services used in certain parts of the world. For example, GSM operates in the 900 MHz band (890 MHz-960 MHz) in Europe and Asia and in the 1900 MHz (sometimes referred to as 1.9 GHz) band in the United States. With present and future demands for multimedia capabilities for mobile phone, data and video access as well as transmission of voice in communication services, the current transmission capacity of mobile networks quickly becomes insufficient.
A universal mobile telecommunication system (hereinafter, referred to as “UMTS”) is a global wireless multimedia system that provides wireless communications having very fast data transmission and provides more flexible functions to users in a form of new kinds of services. Basic requirements of the UMTS network includes higher transmission rate, the number of subscriber access, and larger capacity in the current system, and also more enhanced quality of service, wider coverage area, and a large number of supplementary services in the current mobile communication network.
Wideband CDMA (WCDMA) is a third-generation (3G) mobile wireless technology offering much higher data speeds to mobile and portable wireless devices than narrowband CDMA. WCDMA can support mobile/portable voice, images, data, and video communications at up to 2 Mbps (local area access) or 384 Kpbs (wide area access). The input signals are digitized and transmitted in coded, spread-spectrum mode over a broad range of frequencies. A 5 Mhz-wide carrier is used, compared with 200 Khz-wide carrier for narrowband CDMA.
Universal Mobile Telecommunications Service (UMTS) is another 3G network that can be used to transmit digitally formatted voice, multimedia or other information. As the simplest configuration of the data transmission channel, the UMTS is a telephone or a portable computer that operates almost throughout the world and provides a constant high-speed access to Internet network. The UMTS is capable of transmitting high quality video images. The UMTS system is based on the GSM system and operates at a frequency of about 2 GHz, which is higher than a frequency of a current DCS-1800 network (a 1800 MHz digital cellular system).
GSM is mostly used in Europe and Asia, and CDMA is used mostly in America, China, Korea, India and Taiwan. In an environment in which voice and data communications are enhanced and expanded in world markets, a strong demand exists from international travelers for a “universal telephone” that is operable in many nations. For example, a phone operable in multi-mode such as in GSM and/or WCDMA.